Filter signal



M. G. GRANT FILTER SIGNAL Oct. 15, 1957 Filed April 19, 1955 "TO ENGINE INVENTOR. MICHAEL 6. GRANT United States Pate it FILTER SIGNAL Michael George Grant, Baltimore, Md., assignor to The Briggs Filtration Co., Washington, D. C., a corporation of Maryland Application April 19, 1955, Serial No. 502,305

2 Claims. (Cl. ZOO-81.9)

This invention relates in general to a filter signal and more in particular to a signal indicating device for use in connection with any filter that is of the by-pass type and with oil systems having relief valves located externally.

It is a well known fact that filters employing afilter cartridge, such as those used for cleaning the crank case oil of internal combustion engines, especially the engines of truck and automobiles, become plugged whereby the flow through the cartridge decreases so that at the end of the life of the cartridge the total discharge flow is substantially less than when the cartridge was newly replaced. Also, if for some reason the oil is depleted in the system there is nothing to indicate when this occurs so that the engine may be stopped to prevent damage thereto.

The primary object of the invention is to provide means for signalling the operator when the filter cartridge is plugged thereby decreasing the flow to the extent that liquid is being by-passed around the filter to impede the proper filtration of the oil.

Another object of the invention is the provision of means for signalling the operator when the lubricating system has been depleted of oil.

A further object of the invention is to provide a filter signal which will operate the warning light intermittently under predetermined conditions.

A still further object of the invention is to provide a device for indicating when the cartridge in a filter is unfit for further use.

Another object of the invention is to provide a signal device which will be operable from either the inlet or outlet of the filter.

A still further object is to provide a filter signal of this character of simple and practical construction, which is efficient and reliable in use, relatively inexpensive to manufacture and otherwise well adapted for the purposes for which the same is intended.

With these objects definitely in view, this invention resides in certain novel features of construction, combination and arrangement of elements and portions as will be hereinafter described in detail in the specification, particularly pointed out in the appended claims and illustrated in the accompanying drawings which form a material part of this specification, in which:

Figure 1 is a perspective view of the filter signal with a vertical section cut away, showing also the circuit arrangement for the warning signal;

Figure 2 is a diagram of the lubricating system including the filter signal.

Referring to Figure 1, the numeral 11 represents a signal device having a housing or body portion in two parts 17, 19 which have flanges 21, 23 held together by rivets or bolts 25.

The numeral 27 designates a diaphragm which is disposed between the two parts 17, 19 and held in position by the rivets 25. The diaphragm is provided with a central, metal insert 29 having a calibrated aperture or port 2,810,034 Patented Oct.- 15, 1957 31. The insert is provided with a radial means 33 for receiving the diaphragm and is secured therein by rivets 35.

The lower member 19 has a central, tubular portion 37 provided with a threaded opening or outlet 15. The tubular portion has a bore 39 which terminates in a radial seat 41. A spring 43 is disposed between the insert 29 and radial seat 41 for a purpose to be later described. The lower member may be grounded by the conduit or by line 40.

The upper member 17 has a central tubular portion 45 provided with a threaded opening 47 for receiving a fitting 49 of hard rubber or plastic for insulating the elec trode. The fitting 49 includes a threaded bore 51 adapted to receive the threaded portion 53 of an electrode 55. The bottom end of the electrode is provided with a beveled portion 57 to form a seat which is adapted to close the port 31. A lock nut prevents the electrode from slacking back. A gasket 77 is disposed between the fitting 49 and tubular portion 45 and a gasket 79 is disposed between fitting 49 and the lock nut 75 to provide an oil seal. The top end of the electrode has a conventional terminal 59 which is connected to battery 61 through line 63, indicator light 65, line 67, switch 69 and line 71. The tubular portion is provided with a lateral projection 73 having a threaded opening or inlet 13.

Operation As shown in Figure 2, the oil in the crank case flows to the signal device inlet 13 through line 81, pump 83 and line 85.

Assuming that the cartridge 87 is functioning properly, the oil under normal pressure is sufiicient to force the diaphragm 27 downwardly against the spring 43 thus opening the calibrated opening 31 allowing the oil to flow from the inlet 13 to the cartridge 87 through the calibrated opening 31, outlet 15 and line 89. The oil will flow from the filter 91 back to the engine and crank case through line 93.

When the filter cartridge 87 becomes substantially impervious due to the accumulation of impurities removed from the oil, the oil will by-pass the filter 91 by entering conduit 95, relief valve 97 and pass through conduit 99 to the return line 93.

When the differential pressure in the filter 91 reaches a predetermined amount, at which the cartridge 87 should be replaced, the flow through the filter will decrease or slow down and the diaphragm with the aid of the spring 43 moves upwardly into contact with the electrode 55 thereby grounding the electrode Which closes a circuit from the battery 61 through the indicator light 65 and signals the operator that the cartridge requires replacement. Obviously the indicator light may be remotely located from the filter.

The indicator light will operate intermittently rather than in a steady beam. When the diaphragm moves upwardly into contact with the electrode, the bevel seat 52 is adapted to close the opening 31. The pressure in the filter 91 diminishes allowing the pump pressure to force the diaphragm downwardly breaking the circuit. The oil will again flow through the opening 31 until the pressure in the filter increases and the above cycle then repeats.

When first starting a cold engine the flow of oil through the filter is low and the indicator light will operate only for a few seconds because the viscosity of the oil at starting time is so high that the resulting force on the diaphragm is more than adequate to move it away from the electrode. The insert in the diaphragm will make contact with the electrode only when the flow of oil reaches the minimum point after the oil is up to operating temperature.

It should be noted that the signal device may be located in the. discharge line from the filter as shown in broken lines in Figure 2.

It is obvious that various changes may be made in the form, structure and arrangement of parts withoutdepar-F ing from the spirit of the invention. Accordingly, applicant does not desire to be limited to the specific embodiment disclosed herein primarily for purposes of illustration; but instead, he desires protection falling fairly within the scope of the appended claims.

I claim:

1. A switch comprising, in combination, a housing having a fluid inlet and a fluid outlet, adi'ap'hragm having a central insert with a port and disposed in the-housingbetween the inlet and outlet, an electrode extending into the housing and positioned to normally close the port, resilient means for urging the insertagainst the electrode to close the switch, said diaphragm adapted to 4; move the insert out of contact with the electrode to ope: the switch under a predetermined condition.

2. A switch comprising, in combination, a housin having a fluid inlet and a fluid outlet, a diaphragm having an insert with a port and disposed in the housing between the inlet and outlet, an electrode extending into the housing and positioned to normally close the port, resilient means for urging the insert against the electrode to close the port and switch, said diaphragm adapted to open the contact betweenthe electrode and insert under a normal, rate of flow and intermittently with a lower rate of flow.

References Cited in the file of this patent UNITED STATES PATENTS 2,328,131 Eisler Aug. 31, 1943 2,499,494 Greer Mar. 7, 1950 

